Mutational inactivation of aminoacylase-1 in a small cell lung cancer cell line

Synergistic Interactions of Cannabidiol with Chemotherapeutic Drugs in MCF7 Cells: Mode of Interaction and Proteomics Analysis of Mechanisms

Cannabidiol (CBD), a nonpsychoactive phytocannabinoid, has recently emerged as a potential cytotoxic agent in addition to its ameliorative activity in chemotherapy-associated side effects. In this work, the potential interactions of CBD with docetaxel (DOC), doxorubicin (DOX), paclitaxel (PTX), vinorelbine (VIN), and 7-ethyl-10-hydroxycamptothecin (SN-38) were explored in MCF7 breast adenocarcinoma cells using different synergy quantification models. The apoptotic profiles of MCF7 cells after the treatments were assessed via flow cytometry. The molecular mechanisms of CBD and the most promising combinations were investigated via label-free quantification proteomics. A strong synergy was observed across all synergy models at different molar ratios of CBD in combination with SN-38 and VIN. Intriguingly, synergy was observed for CBD with all chemotherapeutic drugs at a molar ratio of 636:1 in almost all synergy models. However, discording synergy trends warranted the validation of the selected combinations against different models. Enhanced apoptosis was observed for all synergistic CBD combinations compared to monotherapies or negative controls. A shotgun proteomics study highlighted 121 dysregulated proteins in CBD-treated MCF7 cells compared to the negative controls. We reported the inhibition of topoisomerase II β and α, cullin 1, V-type proton ATPase, and CDK-6 in CBD-treated MCF7 cells for the first time as additional cytotoxic mechanisms of CBD, alongside sabotaged energy production and reduced mitochondrial translation. We observed 91 significantly dysregulated proteins in MCF7 cells treated with the synergistic combination of CBD with SN-38 (CSN-38), compared to the monotherapies. Regulation of telomerase, cell cycle, topoisomerase I, EGFR1, protein metabolism, TP53 regulation of DNA repair, death receptor signalling, and RHO GTPase signalling pathways contributed to the proteome-wide synergistic molecular mechanisms of CSN-38. In conclusion, we identified significant synergistic interactions between CBD and the five important chemotherapeutic drugs and the key molecular pathways of CBD and its synergistic combination with SN-38 in MCF7 cells. Further in vivo and clinical studies are warranted to evaluate the implementation of CBD-based synergistic adjuvant therapies for breast cancer.

The mercapturic acid pathway

The mercapturic acid pathway is a major route for the biotransformation of xenobiotic and endobiotic electrophilic compounds and their metabolites. Mercapturic acids (N-acetyl-l-cysteine S-conjugates) are formed by the sequential action of the glutathione transferases, γ-glutamyltransferases, dipeptidases, and cysteine S-conjugate N-acetyltransferase to yield glutathione S-conjugates, l-cysteinylglycine S-conjugates, l-cysteine S-conjugates, and mercapturic acids; these metabolites constitute a "mercapturomic" profile. Aminoacylases catalyze the hydrolysis of mercapturic acids to form cysteine S-conjugates. Several renal transport systems facilitate the urinary elimination of mercapturic acids; urinary mercapturic acids may serve as biomarkers for exposure to chemicals. Although mercapturic acid formation and elimination is a detoxication reaction, l-cysteine S-conjugates may undergo bioactivation by cysteine S-conjugate β-lyase. Moreover, some l-cysteine S-conjugates, particularly l-cysteinyl-leukotrienes, exert significant pathophysiological effects. Finally, some enzymes of the mercapturic acid pathway are described as the so-called "moonlighting proteins," catalytic proteins that exert multiple biochemical or biophysical functions apart from catalysis.

A joint analysis of metabolomics and genetics of breast cancer

Introduction

Remodeling of cellular metabolism appears to be a consequence and possibly a cause of oncogenic transformation in human cancers. Specific aspects of altered tumor metabolism may be amenable to therapeutic intervention and could be coordinated with other targeted therapies. In breast cancer, the genetic landscape has been defined most comprehensively in efforts such as The Cancer Genome Atlas (TCGA). However, little is known about how alterations of tumor metabolism correlate with this landscape.

Methods

In total 25 cancers (23 fully analyzed by TCGA) and 5 normal breast specimens were analyzed by gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry, quantitating 399 identifiable metabolites.

Results

We found strong differences correlated with hormone receptor status with 18% of the metabolites elevated in estrogen receptor negative (ER-) cancers compared to estrogen receptor positive (ER+) including many glycolytic and glycogenolytic intermediates consistent with increased Warburg effects. Glutathione (GSH) pathway components were also elevated in ER- tumors consistent with an increased requirement for handling higher levels of oxidative stress. Additionally, ER- tumors had high levels of the oncometabolite 2-hydroxyglutarate (2-HG) and the immunomodulatory tryptophan metabolite kynurenine. Kynurenine levels were correlated with the expression of tryptophan-degrading enzyme (IDO1). However, high levels of 2-HG were not associated with somatic mutations or expression levels of IDH1 or IDH2. BRCA1 mRNA levels were positively associated with coenzyme A, acetyl coenzyme A, and GSH and negatively associated with multiple lipid species, supporting the regulation of ACC1 and NRF2 by BRCA1. Different driver mutations were associated with distinct patterns of specific metabolites, such as lower levels of several lipid-glycerophosphocholines in tumors with mutated TP53. A strong metabolomic signature associated with proliferation rate was also observed; the metabolites in this signature overlap broadly with metabolites that define ER status as receptor status and proliferation rate were correlated.

Conclusions

The addition of metabolomic profiles to the public domain TCGA dataset provides an important new tool for discovery and hypothesis testing of the genetic regulation of tumor metabolism. Particular sets of metabolites may reveal insights into the metabolic dysregulation that underlie the heterogeneity of breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0415-9) contains supplementary material, which is available to authorized users.

Methionine-induced hyperhomocysteinemia and bleomycin hydrolase deficiency alter the expression of mouse kidney proteins involved in renal disease

SCOPE

Hyperhomocysteinemia (HHcy) induced by dietary or genetic factors is linked to kidney disease. Bleomycin hydrolase (Blmh) metabolizes Hcy-thiolactone to Hcy. We aimed to explain the role of dietary HHcy in kidney disease.

METHODS AND RESULTS

We examined kidney proteome in dietary HHcy and Blmh-knockout mouse models using 2D IEF/SDS-PAGE gel electrophoresis and MALDI-TOF mass spectrometry. We found that the kidney proteome was altered by dietary HHcy and the Blmh(-/-) genotype. Proteins involved in metabolism of lipoprotein (ApoA1), amino acid and protein (Acy1, Hspd1), carbohydrate (Pdhb, Fbp1-isoform 1, Eno1), and energy metabolism (Ndufs8, Ldhd) were down-regulated. Proteins involved in carbohydrate metabolism (Fbp1-isoform 2), oxidative stress response (Prdx2), and detoxification (Glod4) were up-regulated. The Blmh(-/-) genotype down-regulated Glod4 isoform 3 mRNA but did not affect isoform 1 mRNA expression in mouse kidneys, suggesting post-transcriptional regulation of the Glod4 protein by the Blmh(+/+) genotype. Responses of ApoA1, Acy1, Hspd1, Ndufs8, Fbp1, Eno1, and Prdx2 to HHcy and/or Blmh deficiency mimic their responses to renal disease.

CONCLUSION

Our findings indicate that Blmh interacts with diverse cellular processes--lipoprotein, amino acid and protein, carbohydrate, and energy metabolisms, detoxification, antioxidant defenses--that are essential for normal kidney homeostasis and that deregulation of these processes can account for the involvement of HHcy in kidney disease.

Proteomic analysis of rat brains following exposure to electroconvulsive therapy

Electroconvulsive therapy (ECT) is one of the most effective treatments used in psychiatry to date. The mechanisms of ECT action, however, are the least understood and still unclear. As a tool to elucidate the mechanisms of action of ECT, we employed proteomic analysis based on the identification of differentially expressed proteins after exposure to repeated ECT in rat brains. The expression of proteins was visualized by silver stain after two-dimensional gel electrophoresis. Of 24 differentially expressed protein spots (p<0.05 by Student t-test), six different proteins from 7 spots were identified by matrix-assisted laser desorption/ionization time-of flight (MALDI-TOF)/mass spectrometry. Among the identified proteins, there were five dominantly expressed proteins in the ECT-treated rat brain tissues (p<0.05); S100 protein beta chain, 14-3-3 protein zeta/delta, similar to ubiquitin-like 1 (sentrin) activating enzyme subunit 1, suppressor of G2 allele of SKP1 homolog, and phosphatidylinositol transfer protein alpha. The expression of only one protein, ACY1 protein, was repressed (p<0.05). These findings likely serve for a better understanding of mechanisms involved in the therapeutic effects of ECT.

Identification of proteins differentially expressed in the conventional renal cell carcinoma by proteomic analysis

Renal cell carcinoma (RCC) is one of the most malignant tumors in urology, and due to its insidious onset patients frequently have advanced disease at the time of clinical presentation. Thus, early detection is crucial in management of RCC. To identify tumor specific proteins of RCC, we employed proteomic analysis. We prepared proteins from conventional RCC and the corresponding normal kidney tissues from seven patients with conventional RCC. The expression of proteins was determined by silver stain after two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The overall protein expression patterns in the RCC and the normal kidney tissues were quite similar except some areas. Of 66 differentially expressed protein spots (p<0.05 by Student t-test), 8 different proteins from 11 spots were identified by MALDI-TOF-MS. The expression of the following proteins was repressed (p<0.05); aminoacylase-1, enoyl-CoA hydratase, aldehyde reductase, tropomyosin alpha-4 chain, agmatinase and ketohexokinase. Two proteins, vimentin and alpha-1 antitrypsin precursor, were dominantly expressed in RCC (p<0.05).

Tumour-related enzyme alterations in the clear cell type of human renal cell carcinoma identified by two-dimensional gel electrophoresis

To identify tumour-related enzyme alterations we have used 2D-gels to analyse the proteome from dissected malignant and benign kidney areas from patients with clear-cell-type renal carcinoma. The expression of 12 proteins was diminished in tumour. Four proteins were characterized by mass spectrometry and were identified as enoyl-CoA hydratase, alpha-glycerol-3-phosphate dehydrogenase, aldehyde dehydrogenase 1 and aminoacylase-I.

Loss of expression of the DRR 1 gene at chromosomal segment 3p21.1 in renal cell carcinoma

Consistent deletion of DNA sequences in chromosomal band 3p21 observed in a variety of human tumors suggests the presence of one or more tumor suppressor genes within this region. Previously, we reported on the construction of two distinct cosmid contigs and our identification of several new genes within 3p21.1. In our search for tumor suppressor genes from this region, we have cloned a gene that we have called DRR 1 (downregulated in renal cell carcinoma). The gene was first mapped to 3p21.1 by fluorescence in situ hybridization analysis. Further analysis of yeast artificial chromosome clones in 3p14.2-p21.1 refined its localization. DRR 1 spans about 10 Kb of genomic DNA with a 3.5-Kb mature transcript. The putative protein encoded by this gene is 144 amino acids and includes a nuclear localization signal and a coiled domain. The gene showed loss of expression in eight of eight renal cell carcinoma cell lines, one of seven ovarian cancer cell lines, one of one cervical cancer cell line, one of one gastric cancer cell line, and one of one non-small-cell lung cancer cell line. Southern blot analysis did not show any altered bands, indicating that gross structural changes or deletions did not cause the loss of expression. This gene was also found to have reduced expression in 23 of 34 paired primary renal cell carcinomas. Mutational analysis detected three polymorphic sites within the gene, but no point mutations were identified in the 34 primary tumors. However, we did detect base substitutions in 4 of 12 cell lines that had undetectable expression of the gene. We also transfected the gene into DRR 1-negative cell lines and observed clear growth retardation. Our results suggest that loss of expression of the DRR 1 gene may play an important role in the development of renal cell carcinoma and possibly other tumors. Genes Chromosomes Cancer 27:1-10, 2000.